2 (g.d.d.) Subduction at Trenches

Subduction at TrenchesHow can the ocean floor keep getting wider and wider? The answer is that the ocean floor generally does not just keep spreading. Instead, the ocean floor plunges into deep under-water canyons called deep-ocean trenches. At a deep-ocean trench, the oceanic crust bends downward. The process by which ocean floor sinks beneath a deep-ocean trench and back into the mantle is called subduction (sub duk shun). As subduction occurs, crust closer to a mid-ocean ridge moves away from the ridge and toward a deep-ocean trench. Sea-floor spreading and subduction work together. They move the ocean floor as if it were on a giant conveyor belt.